> This change seems to have broken the swig bindings on Mac OS X and Windows.
> Anybody have any ideas why?

As of r35332, this has been resolved. To answer your question though,
SWIG was wrappering 'svn_auth_gnome_keyring_unlock_prompt_func_t'
which is unwanted. Fixing 'build/generator/swig/header_wrappers.py'
to properly ignore the type fixes this issue.